This invention relates to light-transmitting optical fibers and more particularly to a method and apparatus for manufacturing optical fiber ribbons.
There is substantial interest in using light-transmitting optical fibers in future optical communications systems. Their large channel capacity and small diameter make them very attractive alternatives to conventional wire and metallic waveguides.
However, some mechanical and physical characteristics of optical fibers are less desirable and hinder their full development as a feasible light-transmitting medium. Optical fibers tend to be brittle and break at small ultimate elongations which causes total transmission loss. Also, surface abrasion reduces the tensile strength of fibers and increases the chance of fiber fracture. Furthermore, optical fibers are susceptible to optical losses due to various introduced stresses even if the forces are not sufficient to fracture the fibers. Unfortunately, optical fibers in any practical implementation will be subjected to various stresses and deformations during manufacture, packaging, field installation, and service.
While the small size of optical fibers is desirable in terms of space efficiency in replacing wire cables, this small size also renders optical fibers very fragile and difficult to handle individually without mechanical damage. Also, this small size makes fibers difficult to splice; mating fibers must axially align with each other if splicing with low optical losses is to result.
One approach to solving the above difficulties with optical fibers has been to put them in more manageable units such as arranging the fibers in linear arrays and packaging them in some supporting medium to form optical fiber ribbon structures. The fibers are then easier to handle and better protected mechanically as well.
However, ribbon structures can also add optical losses to the light-transmitting optical fibers being packaged. During the manufacture of ribbon structures especially, mechanical damage to the fibers such as abrasion can occur. Also, the ribbon manufacturing process can introduce residual stresses, such as by tensilely loading the optical fibers being packaged.
While ribbon structures can also facilitate splicing of groups of fibers which are more convenient and quicker to connect than individual mating pairs, fibers often are not sufficiently aligned along the ribbon structure to permit gang splicing with low losses. Hence, it is desirable to develop a means for accurately aligning fibers along the entire length of the ribbon being manufactured. Alternatively, an easy approach of locating the fibers in preparation for gang splicing is desired.
Accordingly, it is one objective of this invention to develop a method and apparatus for manufacturing optical fiber ribbons with minimum optical loss to the fibers.
A second objective is to minimize external forces on the fibers during ribbon manufacture.
A third objective is to accurately align the light-transmitting optical fibers in ribbon structures that facilitate gang splicing.
A fourth objective is to develop a simple and convenient method of locating optical fibers into a precise, predetermined array.